The present invention refers to an electrical connector assembly particularly suitable for use in electrical connections located inside the fuel tanks of automotive vehicles of the dual fuels kind, which use different proportions of alcohol and gasoline mixtures, such as electrical fuel pumps and fuel level sensors.
Vehicles running on alcohol and/or gasoline generally comprise an electric pump responsible for pumping the fuel present in the tank to the lines that transport the fuel to the injection valves which inject fuel into the combustion motor. Besides this pump, the vehicles also use a fuel level sensor responsible for providing an electrical signal corresponding to the fuel level present in the vehicle's tank. This kind of electric pump and level sensor are powered by means of electrical cables that run through the tank, being exposed to fuel, and are connected to the electrical terminals of the pump or sensor by way of electrical connectors.
By virtue of the fact that these electrical pumps, level sensors and respective electrical power cables are in direct contact with the fuel, the connection between these and the cables needs to have some kind of sealing that prevents the entry of fuel into the electrical terminals of the pump or the sensor, especially in cases where the use of alcohol fuel is the predominating portion of the bifuel mixture.
Infiltration of fuel inside the connector is problematic due to the fact that the contact of the electrical terminals of the pump or the electrical power cables with the fuel causes chemical and/or electrolytic corrosion of same and consequently the electrical contact of the pump or of the sensor becomes prejudiced. Electrolytic corrosion, however, only occurs if two terminals with opposite polarities are exposed to the same fuel means, generating a difference in potential inside the fuel that provokes electrolysis. This corrosion is more harmful and serious than the simple contact of the electrical terminals with fuel separately.
For this kind of application of fuel pumps and level sensor, it is common to use fourway electrical connectors, having connections to the positive and negative terminals of the pump, and to the positive and negative terminals of the level sensor.
Normally, this kind of electrical connector assembly is mounted on the flange, which has a single cavity or individual cavities with electrical terminals overmolded or mounted on the flange, two of which to a pump and the other two to the level sensor. The connector assembly is formed by a locking part which has a connector molded in a single part around the four aligned pre-tinned electrical terminals. A cover is coupled over the connector to assist in sealing and protecting the electrical terminals. This cover has four cuts which are each traversed by a wire which connects to one of the terminals. Additionally, to each terminal there is connected an inner sealing ring in the junction region between the connector and the cover, to avoid infiltration of fuel directly into the terminals. The connector also has sealing rings on its outer surface which will be encased inside the female part, also to block the entry of fuel inside the connector assembly, in the region of the terminals.
When the locking part is encased into the female part, the connection between the terminals of the locking part and the connection pins of the female part occurs in the single cavity of the locking part. There is no effective physical insulation between these connections, which is extremely harmful to the quality of the electrical contacts and to the durability of the connector assembly. This is because if the fuel penetrates into the cavity, the opposite polarity electrical terminals exposed to the same fuel means will cause an electrolysis reaction, which will provoke the corrosion of these terminals.
Some electrical connector models for an environment with the presence of fuel are already known, and are designed to solve the problem of fuel infiltration in the cables, consequently reducing corrosion of the electrical terminals.
Brazilian patent document PI 0603987-1 filed in the name of Robert Bosch do Brasil refers to an electrical connector assembly for fuel pumps and level sensors for bifuel-type vehicles, which has two insulated chambers for the electrical terminals of the connector, in order to avoid corrosion by electrolysis between the two terminals caused by the difference of potential between the terminals in an environment containing alcohol. The connector assembly has inner sealing stoppers between the inner walls of the insulated chambers and the terminals, and outer sealing stoppers on the outer walls of the insulated chambers and the female connection part.
The drawback of this connector is that it provides an effective sealing only in the region of connection between the locking and female parts of the connector assembly. Additionally, it requires the use of sealing rings that are additional parts that should be manufactured separately because they are then connected to the other components of the connector assembly, which makes the process of manufacturing them more complex, and increases the expense of the end product.
In contrast, this connector assembly does not prevent the infiltration of fuel by capillarity in the cables, which is the phenomenon in which the fuel penetrates into the gap between the protective cover of the cable and the conductive metal wires and moves through this space to the terminal where the metal wires are crimped to a metal contact pin. Therefore, this fuel infiltration does not occur only in the region of coupling between the electrical contacts of the cables and the electrical device to be powered, but rather along the entire length of the cable that is in contact with the fuel in the form of vapor or liquid. This connector of the state of the art does not provide any mechanism that prevents the fuel already infiltrated into the gap between the protective cover of the cable and the metal wires from reaching the contact terminals of the cable.
The Brazilian utility model document MU8802744-9 refers to a seal-tight electrical connector assembly which prevents infiltration of fuel into the electrical terminals. The connector assembly comprises a female part having two reception chambers and two electrical contacts housed inside the female part. The connector also has a locking part with an accommodation that houses the connection ends of two electrical cables, each cable connection end being disposed inside an insulated chamber of the accommodation, the insulated chambers being encasable in a seal-tight manner into a respective reception chamber of the female part. The locking part has metal pins, the body of which presents at least a greater diameter segment than that of the opening of the insulated chambers, disposed near the connection exit opening of the accommodation, and at least an external hollow along its body to house a sealing ring. The locking part also comprises at least a sealing ring mounted by interference in each hollow of the body of the pin, making contact with pressure on the inside of a reception chamber of the female part.
In other words, this document describes the separation of the contacts of the terminals into insulated chambers, but strongly depends on various sealing rings both between the locking and females parts and on the connection pin, in order to avoid fuel infiltration. Additionally, it does not allow the simple withdrawal and substitution of insulated cables or terminals from the connector.
The Brazilian patent document PI0804605-0 refers to known transport aggregates that have a connecting lid, a connecting cover on the connecting lid, a hollow space formed between the connecting lid and the connecting cover, and electrical connections which through the connecting cover extend inwardly of the hollow space, and the electrical connections are respectively provided for in chambers separate from one another in the hollow space. The use of separate chambers for the electrical connections is to avoid completely or at least significantly diminish the corrosion that normally occurs in electrical connections and in non insulated cables, exposed to fuel, during the transport of fuels containing water, such as, for example, ethanol.